Salmonellosis is one of the most commonly reported zoonotic diseases in humans. In the United States alone, it causes an estimated 1.3 million human food-borne illnesses and more than 500 deaths each year (Messens et al., 2013). Salmonella serotypes enteritidis and typhimurium are frequently detected in human infections (Ravel et al., 2010). Salmonellas are widely distributed in nature, and they are commonly carried by wild or farm-animal vectors. Poultry is known to be a major global reservoir of Salmonellas. Salmonella live in poultry gut as transient members of the intestinal microbial population without causing disease. Colonization of Salmonella does not usually affect poultry body weight gain or performance; thus, asymptomatic infection can increase the likelihood of zoonotic transmission to humans through the food chain (Hugas et al., 2014; Mazengia et al., 2014). Chicks can become infected vertically (from adults via the egg to the chick) or horizontally (from the environment, pests, or feed) (Cox et al., 2014; Rodriguez et al., 2006).
Salmonella enterica is one of the two main Salmonella species that causes gastroenteritis in humans. S. enterica is subdivided into 6 subspecies and almost all human infections are caused by subspecies I (enterica). More than 2600 serovars of S. enterica have been identified (Popoff and Le Minor, 1997); however, only a few of these serovars are responsible for most Salmonella infections in human and domestic animals (Porwollik et al., 2004).
The large and growing market for broiler chickens and eggs, and the emergence of antibiotic resistant strains of Salmonella have led to public health concerns, change in government regulation policies in Europe and North America and further demands to enact laws to control Salmonella levels in poultry (Hugas, et al., 2014).
Vaccination strategies in broiler chickens have shown sub-optimal results to-date mostly due to the short life span of the birds. Currently, two types of Salmonella vaccines are commercially available; an attenuated live vaccine and an inactivated vaccine. These vaccines are often administered to both breeder and layer flocks, but their effectiveness depends on the targeted serovar, host species, and whether reduction rather than eradication is the objective (Doyle and Erickson, 2006). These vaccines do not eliminate initial colonization of the mucosal surfaces, particularly in the young bird (Dougan et al., 1988). Effective control depends upon a number of factors, including improved on-farm biosecurity, use of best practices in husbandry and use of vaccination and competitive exclusion products and feed additives. Preventive hygienic measures typically involve establishing effective farm-site biosecurity and poultry house sanitation protocols. Other more targeted strategies are being developed. For instance, a combination of Salmonella-specific lytic phages has been recently approved in Europe for applications in food packaging. Others have proposed and tested inclusion of bacteriocins and/or tailspike phage protein (Chakchouk-Mtibaa et al., 2014; Waseh et al., 2010) in the poultry feed for controlling Salmonella but to date none of these products has been commercialized.
It would be advantageous to provide antibodies or fragments thereof that assist in the reduction, prevention and/or treatment of Salmonella infection.